This invention relates generally to three-dimensional display apparatus and methods, and more particularly to apparatus and methods for producing dynamic stereograms for the clinical assessment and treatment of binocular vision problems.
There are many areas in which it is desirable or necessary to generate three-dimensional displays. Visual depth testing is one such area. The perception of depth in humans (and most animals) is a result of the combination of visual inputs from a pair of horizontally separated eyes, each of which sees a slightly different view of an object within the field of vision. Depth perception is derived from the horizontal disparity between corresponding image points in the two eyes and the brain which resolves the discrepancies between the images seen by each eye and interprets the discrepancies as differences in depth.
Orthoptics is the field of nonsurgical management of binocular vision problems, and includes the clinical assessment and treatment of such problems. An integral part of orthoptics is binocular visual stimulation using stereoptic test patterns for measuring binocular vision functioning and for improving binocular vision through active eye exercises. Such test patterns are typically designed to eliminate all monocular cues so that the image seen by either eye alone contains no information about the stimulus. Random element stereograms meet this requirement. Devices commonly employed for producing such test patterns include those which present stereo slide pairs at adjustable positions relative to the two eyes. Slides are easy to change, and may present a variety of different subjects, including random element stereograms. However, slides are disadvantageous in being limited to a static presentation, ruling out animation and motion in three dimensions, and it is often desirable to employ dynamic stereoptic test patterns, such as dynamic random element stereograms.
The advantages of dynamic random element stereography for the clinical assessment and treatment of binocular vision problems has long been recognized, and equipment capable of producing such stereograms is available. However, available equipment is generally rather complex and expensive, and may involve, for example, a computer system employing a random access memory having a capacity sufficient store data corresponding to each individual element of a video display, a dedicated microprocessor to address and read the memory, and a high speed direct memory access port to a host computer. The host computer contains software for generating the video images to be displayed, calculates the data for each element of the display, causes the data to be stored in memory and to be updated as necessary, and controls the dedicated microprocessor which addresses and reads the memory to supply the data to a video display device for each frame of the display. Since the video display must be generated and refreshed each frame, the software is typically written in assembly language, which further complicates the system and makes changes difficult. A system of this type is disclosed, for example, by Reuss and Kertez, IEEE Transactions on Biomedical Engineering, Vol. BME-28, No. 1, January 1981.
It is desirable to provide apparatus and methods for producing three dimensional video displays, such as dynamic random element stereograms, that avoid the foregoing disadvantages, and it is to this end the present invention is directed.